Boghossian's book is not meant to change the minds of believers but rather the approach he lays out in it should.

In his book, A Manual for Creating Atheists, Peter Boghossian is not writing to Christians. He's writing to atheists. Christians are reading and critiquing his book of course, but the atheists who implement his strategies are taught by him to be respectful of believers as persons, using the Socratic Method. So what's going on here? He uses some rhetoric to get atheists motivated but in actual practice when speaking to Christians, as his own "interventions" demonstrate in the book itself, he advocates being respectful to them and their beliefs. He first motivates then he educates.